Microarray applicator

ABSTRACT

Microarray applicator (10000), a method of using the same and a kit. The microarray applicator comprising a housing (2000), a microarray holder (8100) and a plunger (7000). The plunger comprising a first ridge (7310) and a second ridge (7320), both engagable to a notch (2320). Microarray applicator does not uses springs or pre-biased mechanisms to reduce costs.

BACKGROUND

Microneedle applicators having complex actuation systems, such as thoseusing springs or other stored energy devices to cause the microneedlesto come into contact with the skin, are known. Such applicators areexpensive to manufacture so they are designed to be used multiple times.They also have complex components, so they are expensive to replace orrepair.

SUMMARY

A microarray applicator can include a housing, the housing having afirst major surface configured to positioned towards skin and definingthe bottom of the housing, a second major surface opposite the firstmajor surface and defining the top of the housing, a cavity extendingthrough the first and second major surfaces, and an interior surfacedefining the cavity. The interior surface can have one or more ridges,each having a ridge width, as well as a ridge height defined by thedistance between the ridge and the first major surface, and a holderlocated between the first and second major surfaces for holding at leastpart of a microarray device within the housing.

The microarray applicator can further include a plunger. The plunger hasa top, a bottom, and one or more sides. A first set of one or morenotches is located proximate to the bottom of the plunger, each of theone or more notches in the first set of one or more notches beinglocated substantially the same distance from the bottom of the plunger,and having a first depth into one or more sides, such that when thefirst notch is fully engaged with the ridge in the housing a first forcecan release the first notch in a direction towards the bottom of thehousing and a second force can release the first notch in a directiontowards the top of the housing, the first force being substantially thesame as the second force. The plunger also has a second set of one ormore notches located proximate to the top of the plunger, each of theone or more notches in the second set of one or more notches beinglocated substantially the same distance from the top of the plunger, andextending a second depth into the one or more sides in such that whenthe second notch is fully engaged with the ridge in the housing a thirdforce can release the second notch in a direction towards the bottom ofthe housing and a fourth force can release the second notch in adirection towards the top of the housing, the third force beingsubstantially the same as the fourth force.

The second depth is equal to or greater than the first depth, and equalto or less than the ridge width. The distance between the first set ofone or more notches and the second set of one or more notches is greaterthan the notch height. The plunger is slidably engageable with thecavity in the housing to be moveable between a first position whereinthe first set of one or more notches is engaged with the one or moreridges in the housing and the bottom of the plunger does not extendbelow the first major surface of the housing, and a second positionwherein the second set of one or more notches is engaged with the one ormore ridges in the housing and the bottom of the plunger extends belowthe first major surface of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top-down view of a housing;

FIG. 2A is a cut-away side view of a housing;

FIG. 2B is a detailed view of a portion of the housing shown in FIG. 2A;

FIG. 3 is a cut-away side view of a housing;

FIG. 4 is a bottom view of a housing;

FIG. 5 is a three-quarter profile view of a housing;

FIG. 6 is a three-quarter view of a plunger;

FIG. 7A is a side view of a plunger;

FIGS. 7B and 7C are detailed view of portions of the plunger of 7A,shown from a cut-away side view;

FIG. 8A is a three-quarter bottom view of a microarray carrier with apatch;

FIG. 8B is a three-quarter bottom view of a microarray carrier without apatch;

FIG. 9A is a cut-away side view of an assembled plunger and housing in afirst position;

FIG. 9B is a detailed view of a portion of FIG. 9A;

FIG. 9C is a cut-away side view of an assembled plunger and housing in asecond position;

FIG. 10A is a cut-away side view of an assembled plunger, housing, andmicroarray carrier; and

FIG. 10B is a cut-away side view of an assembled plunger, housing, andmicroarray carrier being applied to a skin surface.

DETAILED DESCRIPTION

Throughout this disclosure, singular forms such as “a,” “an,” and “the”are often used for convenience; however, it should be understood thatthe singular forms are meant to include the plural unless the singularalone is explicitly specified or is clearly indicated by the context.

Positional terms such as “top” and “bottom” or “left” and “right” arenot used herein in reference to position with respect to the ground, theuser, the floor, the earth, or the direction of a gravitational pull.Instead, these terms are used as relative terms to refer to opposing orapproximately opposing sides or portions of an object. For example,while the “top” of an object is understood to be opposing orapproximately opposing the “bottom,” it is not necessary that the“bottom” be disposed closer to the ground that the “top.”

A microneedle array applicator can include a housing and a plunger. Thehousing and the plunger can be made of any suitable material, but aremost typically plastic. Common plastics that can be used includepolyethylene, such as high density polyethylene, polypropylene, nylon,such as nylon 6,6, and the like. The housing and the plunger need not bemade of the same material, although this is most common.

The housing can have a first major surface that is configured to bepositioned towards the skin and defining a bottom of the housing. Thefirst major surface is configured to releaseably engage with amicroneedle device, particularly a microarray carrier portion of amicroarray applicator.

The housing can also have a second major surface opposite the firstmajor surface and defining a top of the housing.

The housing can have a cavity that extends through the first and secondmajor surfaces. An interior surface can define the cavity. The interiorsurface can have one or more ridges. The one or more ridges typicallyhave a ridge height, which is defined by the distance between the one ormore ridges and the first major surface. In most cases, the cavity willhave an annular shape, not including the one or more ridges, and therewill be only one ridge that forms a circle around the entire interiorsurface. The entire ridge in this case has the same ridge height. In thecases where the cavity has another shape, for example when the cavityhas a square, triangular, or other cross-section, then there will bemore than one ridge, one ridge per side of the cavity, and each of theridges will have the same ridge height.

The housing can also include a holder located between the first andsecond major surfaces for holding at least part of a microarray devicewithin the housing. The holder can have any suitable configuration,which will depend in part on the configuration of the microarray devicethat it is designed to hold. Some exemplary configurations are depictedin U.S. Patent Application Publication No. US2016/0235958, particularlyin FIGS. 8, 9, 10, 11, 12, 13, 14, and 15, and in PCT Publication No.WO02/30300, particularly in FIG. 16. One particular configuration forthe holder is shown in the Figures of this disclosure, although itshould be understood that other configurations are possible. In theconfiguration depicted in the Figures of this disclosure, the holder isin the form of a slot in the housing, the bottom of the slot beingdefined by the first major surface, and the top of the slot beingdefined by an additional surface. The microneedle array device can fitwithin the slot and slideably engage with the holder. Groves can bepresent in the slot to engage with the microneedle array device.

In many cases, depending on the configuration of the holder, the firstmajor surface does not extend all the way across the housing. In suchcases, the first major surface can, for example, extend only part of theway across the housing, extend only along parts of one or more sides oredges of the housing, and the like. Nonetheless, even in cases where thefirst major surface is part of the holder, the first major surface willtypically be below the portion of the housing that is configured toreceive the microneedle array device.

The plunger can have a top and a bottom, as well as one or more sides.The plunger is configured to slideably engage with the cavity in thehousing. In particular, the bottom of the plunger can be placed withinthe cavity in the housing. Thus, the shape of the plunger will depend onthe shape of the cavity of the housing. In most cases the interiorcavity of the housing has a circular cross-section, and thus the plungeralso has a circular cross-section, and is cylindrical in shape,excluding the ridges.

The plunger can have a first set of one or more notches locatedproximate to the bottom of the plunger, all of which are locatedsubstantially the same distance from the top of the plunger. The firstset of one or more notches have a first depth into the one or more sidesof the plunger. The first width is equal to or less than the ridgewidth. The first set of one or more notches is configured such that,when fully engaged with the ridge in the housing, a first force canrelease the first notch in a direction towards the bottom of the housingand a second force can release the first notch in a direction towardsthe top of the housing, the first force being substantially the same asthe second force. The first and the second forces are substantially thesame, such that they preferably differ by no more than 10%. This istypically accomplished by providing a first and second notch with aprofile that is substantially rotationally symmetric about an axissubstantially normal to the side of the plunger adjacent to the notch.“Substantially rotationally symmetric” refers to rotational symmetrythat is within manufacturing tolerances, particularly to a rotationalsymmetry that is greater than 90% symmetrical, and even moreparticularly to rotational symmetry that is greater than 95%.“Substantially normal,” it is meant that the angle between axis and theside of the plunger is approximately 90°, and in particular cases theangle is from 80° to 100°.

The plunger can also have a second set of one or more notches locatedproximate to the top of the plunger. The second set of one or morenotches is configured such that, when fully engaged with the notch inthe housing, a third force can release the ridge in a direction towardsthe bottom of the housing and a fourth force can release the ridge in adirection towards the top of the housing, the third force beingsubstantially the same as the fourth force. The third and fourth forcesare substantially the same, and particularly differ by no more than 10%.This is typically accomplished by providing a second notch with aprofile that is substantially rotationally symmetric about an axissubstantially normal to the side of the plunger adjacent to the ridge.“Substantially rotationally symmetric” refers to rotational symmetrythat is within manufacturing tolerances, particularly to a rotationalsymmetry that is greater than 90% symmetrical, and even moreparticularly to rotational symmetry that is greater than 95%.“Substantially normal,” it is meant that the angle between axis and theplunger is approximately 90°, and in particular the angle is from 80° to100°. The second width is equal to or less than the ridge width.

The first and second set of one or more notches are separated by adistance. The distance between the first and second sets of one or morenotches is greater than the ridge height.

The shape of the plunger can vary depending on the shape of the cavityin the housing such that the plunger can slideably engage with thecavity. Typically, when the cavity has a circular cross-section, theplunger also has a circular cross-section. In this case the plunger canbe cylindrical. When the plunger is referred to as being cylindrical,this does not include the first and second sets of one or more notchesor the optional head (discussed below), which can extend from theplunger making the overall plunger not a perfect cylinder. When theplunger is cylindrical, there is typically only one notch in the firstset of one or more notches and only one ridge in the second set of oneor more notches.

The plunger can slideably engage with the cavity in the housing. Theplunger is moveable within the cavity between a first position and asecond position within the cavity. In the first position, the first setof one or more notches is engaged with the one or more ridges in theinterior of the cavity of the housing, for example, to releasablyinterlock the plunger with the housing. In the first position, thebottom of the plunger does not extend below the first major surface ofthe housing.

In the second position, the second set of one or more notches engageswith the one or more ridges on the interior surface of the cavity, forexample to releasably interlock the plunger with the housing. In thisposition, the bottom of the plunger extends below the first majorsurface of the housing. The bottom of the plunger extends far enoughbelow the first major surface of the housing that it is capable ofejecting a microneedle patch from a microarray device, when a microarraydevice, such as a microarray device as described herein, is in theholder of the housing.

The top of the plunger can, in some cases, comprise a head. Whenpresent, the head typically extends beyond the sides of the plungerfarther than the cavity in the housing. Thus, the head can serve toblock the top of the plunger from entering the housing. The head can beconfigured in any suitable shape, but most commonly has a mushroom-capshape. The head of the plunger, if present, can also make it easier fora user to push the plunger into the housing and from the first positionto the second position by providing an increased surface area on whichto push. The head of the plunger can also prevent the plunger frommoving through the bottom of the housing by abutting the second majorsurface of the housing when the plunger is in the second position. Thehead of the plunger is not required, and in some cases it is notpresent.

Typically, the applicator does not include an energy storage device,such as a spring, for moving the plunger from the first position to thesecond position or from the second position back to the first position.Instead, the force of a user pushing on the top of the plunger, such asthe head of the plunger when present, can move the plunger from thefirst position to the second position.

A microarray device can engage with the holder of the housing such thatat least a portion of the microarray device is releaseably restrainedwithin the housing. The microarray device will typically have amicroarray carrier, which is typically plastic but can be any suitablematerial including metal or others, that carries a microneedle patch.The microneedle patch is typically in the form of a flexible sheet withmicroneedles protruding therefrom. The term “microneedles” refers toneedles or similar projections having a size on the microscale; otherdisclosures have used the term “microprotrusions” in the same sense, inwhich case the term microneedles is intended to include suchmicroprotrusions. Microneedles can be hollow or solid, and can even bedissolvable within the body. When hollow, the microneedles will oftencontain one or more active agents, often along with optional excipients,within the microneedles. When solid, the microneedles will often containa coating of one or more active agents, often along with optionalexcipients. When dissolvable, the microneedles will often be made out ofa dissolvable matrix having one or more active agents, often along withoptional excipients, in the matrix. The microneedle patch is supportedby the microneedle array carrier, but it can be ejected from the carrierin use.

In use, the bottom of the plunger can be inserted into the cavity.Pushing on the top of the plunger can move the plunger to the firstposition wherein the first set of one or more notches is engaged withthe ridge in the interior of the cavity. A microneedle device can beplaced within the holder (either before or after inserting the plungerinto the first position). The second first major surface of the actuatorcan be placed against the object that is to receive the microneedles,which is usually skin, such as the skin of a subject, but can also beother things such as testing device (e.g., for testing the velocity ofthe plunger or pressure applied by the plunger), an eye, and the like.The plunger can be inserted and moved to the first position eitherbefore or after the second major surface is placed against the skin.

A force sufficient to move the plunger from the first position to thesecond position is applied to the top of the plunger. Typically, thisforce is sufficient to eject the microneedle patch from the microneedledevice, such as to detach the microneedle patch from the microarraycarrier, and also sufficient such that the microneedles can pierce theskin of a subject. The required force will vary depending on theparticular application, but it can be controlled by varying the depth ofthe notch and the width of the ridge, as well as the dimensions of theridge and notch. When the first depth of the first set of one or morenotches, and the corresponding depth of the ridge, is larger, then moreforce is required to disengage the first set of one or more notches fromthe ridge and move the plunger to the second position increases. Whenthe first depth of the first set of one or more notches, and thecorresponding width of the ridge, is smaller, then less force isrequired to disengage the first set of one or more notches from theridge and move the plunger to the second position. An increased forcerequirement to move the plunger from the first to the second positioncan provide a greater velocity of the plunger, which in turn increasesthe force applied by the microneedles on the skin. Thus, the velocity,for example, of the plunger and the microneedles when the microneedlepatch ejects from the applicator and contacts the skin, can becontrolled by varying the first width.

Once the plunger has moved to the second position, that is, the secondset of notches is engaged with the ridge, continued downward pressure onthe plunger provides a pressure on the microneedle patch. The pressureprovided can be controlled by way of increasing or decreasing the secondwidth of the second set of one or more ridges.

After ejecting the microneedle patch, the plunger can be re-set foranother use. To reset the plunger the remaining portion of themicroneedle device (that is, the portion that was not ejected) can beremoved from the holder in the housing. The bottom of the plunger canthen be pushed back up towards the top of the housing until the plungerreturns to the first position. A new microneedle device can be placed inthe holder, and the microneedle applicator can be used again. However,because the microneedle applicator is a simple design that isinexpensive to manufacture and requires no expensive materials, themicroneedle applicator can be designed for a single-use only, and can bediscarded after use.

Typically, no stored energy devices are used during the process. Forexample, in most cases no springs or chemical systems are needed to movethe plunger between the first and second positions. In the case where astored energy device is used, it is typically not an integratedcomponent of the actuator. Instead, it is usually a separate device thatis used to help push the plunger, for example, in cases where the userdoes not have sufficient strength to push the plunger hard enough tomove it from the first to the second position. In most cases, no storedenergy device of any type is used.

In some cases, when sufficient force is applied to the plunger, thesecond set of notches can disengage with the ridge and the plunger canmove downwards past the second position. When this is a concern, thehead of the plunger can be useful. For example, the head of the plunger,which typically extends beyond the sides of the plunger and the cavityof the housing, can stop the plunger from proceeding too far into thehousing, for example, it can stop the top of the plunger from enteringthe housing.

Turning now to the figures, FIG. 1 is a top-down view of housing 1000wherein second major surface 1100 and cavity 1200 are visible. In thisFigure, cavity 1200 has a circular cross-section. Other shapes are alsopossible.

FIG. 2A is a cut-away side view of housing 2000, featuring first majorsurface 2100 and opposing second major surface 2200. Cavity 2300 extendsthrough the entire housing 2000, including featuring first major surface2100 and second major surface 2200. Note that in this Figure, firstmajor surface 2100 does not extend all the way across housing 2000.Holder 2400 is, in this Figure, present in the form of groves in housing2000 for receiving and retaining a microneedle array device (not shown).Cavity 2300 features interior surface 2310 and notch 2320. Notch 2320 ischaracterized notch height 2322, which is the distance between the notchand first major surface 2100.

FIG. 2B is a blow-up of a portion of FIG. 2, wherein notch 2320 isfeatured in more detail. Notch depth 2321, the depth that notch 2320extends into interior surface 2310, is visible in this Figure.

FIG. 3 is a cut-away side view of housing 3000, featuring first majorsurface 3100, second major surface 3200 and cavity 3300 extendingthrough the entire housing 3000 including featuring first major surface3100 and second major surface 3200. In this Figure, first major surface3100 extends further across housing 3000 than the corresponding firstmajor surface 2100 in FIG. 2. Holder 3400 is, in this Figure, present inthe form of groves in housing 3000 for receiving and retaining amicroneedle array device (not shown). Cavity 3300 features interiorsurface 3310 and notch 3320.

FIG. 4 is a bottom view of housing 4000, featuring first major surface4100, second major surface 4200, and cavity 4300. A holder (not shown)can be present in the form of slots for holding the microneedle arraydevice within the housing.

FIG. 5 is a three-quarter view of housing 5000, wherein the first majorsurface is not visible, but second major surface 5200 and cavity 5300are visible. A portion of notch 5320 is visible within cavity 5300. Aportion of holder 5400 for holding a microneedle array device withinhousing 5000 is also visible.

FIG. 6 is a side view of plunger 6000, featuring top 6100, bottom 6200and side 6300. In FIG. 6 the plunger 6000 is approximately cylindrical,so there is only one side 6300, but if the plunger were shapeddifferently it could have more than one side. On the side 6300 is afirst ridge 6310 located proximate to the bottom 6200 of the plunger6000 and a second ridge 6320 located proximate to the top 6100 of theplunger 6000. In FIG. 6, first ridge 6310 and second ridge 6320 arecontinuous around the entire side 6300 of plunger 6000, however otherconfigurations are possible. For example, first ridge 6310 could befirst set of multiple ridges the same distance from bottom 6200.Likewise, second ridge 6320 could be a second set of multiple ridges thesame distance from top 6100.

FIG. 7a is a side view of plunger 7000, featuring a top that is presentas head 7110, which extends outward past the side 7300, as well asbottom 7200. In this Figure, the plunger 7000 is approximatelycylindrical, so there is only one side 7300, but if the plunger wereshaped differently it could have more than one side. On the side 7300 isa first ridge 7310 located proximate to the bottom 7200 of the plunger7000 and a second ridge 7320 located proximate to the top, which ispresent as head 7110 of the plunger 7000. In this Figure, first ridge7310 and second ridge 7320 are continuous around the entire side 7300 ofplunger 7000, however other configurations are possible. For example,first ridge 7310 could be first set of multiple ridges the same distancefrom bottom 7200. In the same way, second ridge 7320 could be a secondset of multiple ridges the same distance from the top, which is in theform of head 7110.

FIG. 7b is a detail of second ridge 7320 and side 7300 shown from across-section cut-away perspective. Second ridge 7320 extends secondwidth W₂ from side 7300 and has a profile that is substantiallyrotationally symmetric about axis X₂. Axis X₂ is substantially normal toside 7300, and forms angle A₂ with side 7300. Angle A₂ is 90° in thisFigure, though other substantially normal angles are possible. Secondwidth W₂ is equal to or less than the notch depth of the housing withwhich plunger 7000 is to be used.

FIG. 7c detail of first ridge 7310 and side 7300 shown from across-section cut-away perspective. First ridge 7310 extends first widthW₁ from side 7300 and is has a profile that is substantiallyrotationally symmetric about axis X₁. Axis X₁ is substantially normal toside 7300, and forms angle A₁ with side 7300. Angle A₁ is 90° in thisFigure, though other substantially normal angles are possible. Secondwidth W₁ is equal to or less than the notch depth of the housing withwhich plunger 7000 is to be used.

FIG. 8A is a three-quarter bottom view of microarray carrier 8000,including microarray holder 8100 as shown in FIG. 8A as well asmicroneedle patch 8200. Microneedle patch 8200 includes a centralportion 8210 featuring a plurality of microneedles 8211 disposed onflexible backing 8220. While the plurality of central portion 8210 isshown as being roughly circular, other shapes are possible. Further,whereas the plurality of microneedles 8211 are shown as being arrangedin a particular manner, other arrangements are possible. Any suitablenumber of microneedles can be used, and the microneedles may be solid,hollow, or a mixture of solid and hollow. When the microneedles aresolid microneedles, such as those described in U.S. Patent ApplicationPublication No. US2005/0246214, then the microneedle patch 8200typically has 90 to 1,200 microneedles, such as greater than 200microneedles, greater than 300 microneedles, greater than 400microneedles, less than 500 microneedles, or less than 400 microneedleson the patch, although any desired number of microneedles can be used.When the microneedles are hollow, such as those described in U.S. PatentApplication Publication No. US2016/0151616, then the microneedle patch8200 typically has 3 to 30 microneedles, most often 12 microneedles,although any desired number of microneedles can be used.

FIG. 8B is a three-quarter bottom view of microarray holder 8100,featuring tabs 8101, 8102, 8103, and 8104, which can serve to retain amicroneedle patch, though no microneedle patch is shown in this Figure.Other elements for restraining a microneedle patch, such as one or moreridges or notches, could be used in a related configuration. Handle 8110is a convenient feature for manipulating microarray holder 8100, forexample, for placing it within a housing as described herein.

FIG. 9A is a cut-away side view of assembled microarray applicator 9000featuring housing 2000 (shown separately in FIG. 2) and plunger 7000(shown separately in FIG. 7A). Plunger 7000 is in a first position,wherein first ridge 7310 of plunger 7000 is engaged with notch 2320 ofhousing 2000. Second ridge 7320 of plunger 7000 is outside housing 2000.FIG. 9B is a blow-up showing the interaction of first ridge 7310 andnotch 2320 in more detail. Bottom 7200 of plunger 7000 does not extendbelow first major surface 2100 of housing 2000.

In use, pressing plunger 7000 in the direction of first major surface2100 of housing 2000 with sufficient force to disengage first ridge 7310of plunger 7000 is engaged with notch 2320 of housing 2000 can moveplunger 7000 to a second position.

FIG. 9C is a cut-away side view of assembled microarray applicator 9000featuring housing 2000 (shown separately in FIG. 2) and plunger 7000(shown separately in FIG. 7A). Plunger 7000 is in a second position,wherein second ridge 7320 of plunger 7000 is engaged with notch 2320 ofhousing 2000. Bottom 7200 of plunger 7000 extends below first majorsurface 2100 of housing 2000.

FIG. 10A is a cut-away side view of assembled microarray applicator10000, which is similar to microarray applicator 9000 as shown in FIG.9A but also includes microarray device 8000, which is retained withinhousing 2000 by virtue of microarray holder 8100 being engaged withholder 2400. Microarray patch 8200 and flexible backing 8220 arepositioned such that the central portion 8210 has microneedles 8211protrude in the direction opposite from the bottom 7200 of plunger 7000.Bottom 7200 of plunger 7000 sits on or, more commonly, slightly abovemicroarray patch 8200. In this Figure, plunger 7000 is in a firstposition, having first ridge 7310 engaged with notch 2320. Handle 8110(not shown) is preferably present as a component of microarray holder8100 for ease of use.

FIG. 10B is a cut-away side view of assembled microarray applicator10000 after activation, wherein plunger 7000 is in a second positionsuch that second ridge 7320 is engaged with notch 2320. Here, bottom7200 of plunger 7000 extends below first major surface 2100 of housing2000, and has ejected microarray patch 8200, thereby applyingmicroneedles 8211 to substrate 10100, which is typically the skin of asubject. In practice, a user can maintain contact between microneedles8211 and substrate 10100 by continuing to apply pressure on plunger7000.

Once microarray patch 8200 has been ejected from housing 2000, themicroarray applicator can be reused. To do so, microarray holder 8100can be removed from holder 2400, for example by using handle 8110 (notshown in FIGS. 10A and 10B). Plunger 7000 can then be moved from thesecond position to the first position by pushing on bottom 7200 ofplunger 7000 until first ridge 7310 engages with notch 2320.

The applicator as described herein is inexpensively manufactured, forexample, all of the components can be made with simple dies by extrudinginexpensive plastics such as polypropylene. Thus, the applicator iseconomical to be used as a single-use device. It can also be re-used, inwhich case there is little chance of requiring expensive maintenance orrepair because it does not contain any complex parts. Further, becauseit can be easily used by an operator without the need for complexpriming steps, it can be viable for an operator who is not a medicalprofessional to use the disclosed applicator, allowing easy applicationof a microneedle patch without the need for a medical professional toadminister it.

1. A microarray applicator comprising: a housing, the housingcomprising: a first major surface configured to positioned towards skinand defining the bottom of the housing, a second major surface oppositethe first major surface and defining the top of the housing, a cavityextending through the first and second major surfaces, an interiorsurface defining the cavity, the interior surface comprising one or morenotches having a notch depth, a notch height defined by the distancebetween the notch and the first major surface, and a holder locatedbetween the first and second major surfaces for holding at least part ofa microarray device within the housing; a plunger, the plungercomprising: a top, a bottom, and one or more sides, a first set of oneor more ridges located proximate to the bottom of the plunger, each ofthe one or more ridges in the first set of one or more ridges beinglocated substantially the same distance from the bottom of the plunger,and extending a first width from the one or more sides, such that whenthe second ridge is fully engaged with the notch a first force canrelease the ridge in a direction towards the bottom of the housing and asecond force can release the ridge in a direction towards the top of thehousing, the first force being substantially the same as the secondforce, and a second set of one or more ridges located proximate to thetop of the plunger, each of the one or more ridges in the second set ofone or more ridges being located substantially the same distance fromthe top of the plunger, and extending a second width from the one ormore sides in such that when the second ridge is fully engaged with thenotch a third force can release the ridge in a direction towards thebottom of the housing and a fourth force can release the ridge in adirection towards the top of the housing, the third force beingsubstantially the same as the fourth force; wherein the second width isequal to or greater than the first width, the second width is equal toor less than the notch depth, the distance between the first set of oneor more ridges and the second set of one or more ridges is greater thanthe notch height, and the plunger is slidably engageable with the cavityin the housing to be moveable between a first position wherein the firstset of one or more ridges is engaged with the one or more notches in thehousing and the bottom of the plunger does not extend below the firstmajor surface of the housing, and a second position wherein the secondset of one or more ridges is engaged with the one or more notches in thehousing and the bottom of the plunger extends below the first majorsurface of the housing.
 2. The microarray applicator of claim 1, whereinthe holder is in the form of a slot in the housing.
 3. The microarrayapplicator of claim 1, wherein the cavity has an annular shape and theone or more notches in the housing are a single notch that forms acircle around the entire interior surface.
 4. The microarray applicatorof claim 3, wherein the plunger is approximately cylindrical, the firstset of one or more ridges is one ridge that forms a circle around theplunger, and the second set of one or more ridges is one ridge thatforms a circle around the plunger.
 5. The microarray applicator of claim1, wherein the plunger top comprises a head that extends beyond the oneor more sides of the plunger farther than the cavity in the housing. 6.The microarray applicator of claim 5, wherein the plunger top abuts thesecond major surface of the housing when the plunger is in the secondposition.
 7. The microarray applicator of claim 1, 1, wherein theplunger is adapted to move from the second position to the firstposition when sufficient force is applied to the bottom of the plungerin the second position.
 8. The microarray applicator of claim 1, whereinthe microarray device does not include an energy storage device.
 9. Themicroarray applicator of claim 1, further comprising a microneedledevice, the microneedle device comprising one or more microneedles. 10.The microarray applicator of claim 9, wherein the microneedle devicecomprises: a microarray patch having one or more microneedles protrudingtherefrom; and a microarray carrier that releasably retains themicroarray patch.
 11. The microarray applicator of claim 10, wherein themicroneedles protrude from a central portion of a flexible backing ofthe microarray patch.
 12. The microarray applicator of claim 10, whereinthe microarray carrier further comprises a plurality of tabs thatreleasably retain the microarray patch.
 13. A kit comprising themicroarray applicator of claim 1 and a microneedle device, themicroneedle device comprising: a microarray patch having one or moremicroneedles protruding therefrom; and a microarray carrier thatreleasably retains the microarray patch.
 14. A method of ejecting one ormore microneedles from a microarray applicator, the method comprising:inserting a microneedle device into the holder of the housing of themicroarray applicator of claim 1; and moving the plunger of themicroarray applicator from the first position to the second position.15. The method of claim 14, wherein the microneedle device comprises: amicroarray patch having one or more microneedles protruding therefrom;and a microarray carrier that releasably retains the microarray patch;wherein moving the plunger from the first position to the secondposition releases the flexible patch from the microarray carrier andejects the microarray patch below the second major surface of thehousing.
 16. The kit of claim 13, wherein the plunger top abuts thesecond major surface of the housing when the plunger is in the secondposition.
 17. The kit of claim 13, wherein the microarray device doesnot include an energy storage device.
 18. The kit of claim 13, whereinthe microneedle device comprises: a microarray patch having one or moremicroneedles protruding therefrom; and a microarray carrier thatreleasably retains the microarray patch.
 19. The method of claim 14,wherein the plunger top abuts the second major surface of the housingwhen the plunger is in the second position.
 20. The method of claim 14,wherein the microarray device does not include an energy storage device.